Both vow to return to the show eventually. “By pursuing my first passion of music during the break, I am also able to come back and offer even more to my team on The Voice in the future,” Aguilera said in a statement.

“I will return for season five and will be watching season four,” said Green.

“We are thrilled to welcome Usher and Shakira to The Voice,” Robert Greenblatt, the chairman of NBC Entertainment, said in statement. “Doing two back-to-back cycles of this show requires a tremendous amount of time and we are happy to accommodate the commitments made by Christina and Cee Lo.”